chess. The Circular Chess known as "al-Muddawara", "ar Rumiya" or "the Byzantine chess". Historical circular chess Rules One set of rules for medieval circular chess is from the Persian author Muhammad ibn Mahmud Amuli's 'Treasury of the Sciences' (1325). In this version, called shatranj al-muddawara (circular chess) or shatranj ar-Rūmīya (Roman or Byzantine chess), the game uses a board with four concentric rings, each split into 16 spaces. The Board contains 64 squares. With an algebraic notation in the round board, in letters of 4 rings ABCD and every space with a number from 1 to 16. A game of chess is played between two players; each has 16 pieces, white, and black opponents of calls. The purpose of Circular Chess is to position their chess pieces in order to checkmate the opponent's king, ending the game. The game uses the same pieces as shatranj. The king and the counselor on the inner ring, next to each other. The next ring has the elephants, the next ring has the knights, and the last ring has the rooks. A single row of 4 pawns flanks each side of the central pieces. The king of one side "faces" the counselor of the other (a shorter path is between the king of one side and the counselor of the other than between the kings of the two sides). Movement is the same as shatranj, except that, if two pawns from the same side, going in opposite directions, end up being blocked by each other, the opponent may remove both pieces, which does not use the opponent's turn. As there is no back row, there is no promotion. A stalemate is a victory for the stalemating player. A bare king is a loss for the player who only has the king left unless, in the next turn, the player can also impose a bare king, at which point the game is a draw. Citadel chess A variant of this game attested by Muhammad ibn Mahmud Amuli has two "citadel" spaces in the centre of the board and a different starting setup. In the citadel game, if a king reaches the citadel, a draw is forced. Modern circular chess Rules The starting position is essentially obtained from that of orthodox chess by cutting the board in half and bending the two halves to join at the ends. Two lines are marked on opposite sides of